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Message-ID: <e5d579d8ef832fbc133e96746ceb6edbd0870cc2.camel@perches.com>
Subject: Re: [PATCH] include/linux/compiler*.h: make compiler-*.h mutually
 exclusive
From:   Joe Perches <joe@perches.com>
To:     Nick Desaulniers <ndesaulniers@google.com>,
        Kees Cook <keescook@chromium.org>, asmadeus@codewreck.org,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Masahiro Yamada <yamada.masahiro@socionext.com>
Cc:     Jonathan Corbet <corbet@lwn.net>, Arnd Bergmann <arnd@arndb.de>,
        dwmw@amazon.co.uk, LKML <linux-kernel@vger.kernel.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Will Deacon <will.deacon@arm.com>,
        Geert Uytterhoeven <geert@linux-m68k.org>,
        Ingo Molnar <mingo@kernel.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        daniel@iogearbox.net, hpa@zytor.com
Date:   Thu, 23 Aug 2018 14:19:06 -0700
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On Thu, 2018-08-23 at 14:03 -0700, Nick Desaulniers wrote:
> One reply for a bunch of the various threads, to keep the number of emails down:
> 
> On Wed, Aug 22, 2018 at 5:20 PM Joe Perches <joe@perches.com> wrote:
> > On Wed, 2018-08-22 at 16:37 -0700, Nick Desaulniers wrote:
> > > +/* Compiler specific macros. */
> > >  #ifdef __clang__
> > >  #include <linux/compiler-clang.h>
> > 
> > probably better as
> > 
> > #if defined(__clang)
> > 
> > to match the style of the #elif defined()s below it
> 
> Hi Joe,
> Thanks for the feedback. I always appreciate it.  If you have some
> cleanups, want to send them to me, and I'll bundle them up for a PR?
> I'm ok with that change.
> 
> > > +#ifdef __GNUC_STDC_INLINE__
> > > +# define __gnu_inline        __attribute__((gnu_inline))
> > > +#else
> > > +# define __gnu_inline
> > > +#endif
> > 
> > Perhaps __gnu_inline should be in compiler-gcc and this
> > should use
> > 
> > #ifndef __gnu_inline
> > #define __gnu_inline
> > #endif
> 
> Not this case; it's how we get gnu89 semantics for `extern inline` is
> not compiler specific (therefor should not go in a compiler specific
> header).

It's not possible to know that compilers support what
__attribute__((<foo>)) and at what version that support
exists unless it is specified somewhere.

As far as I can tell,  gnu_inline is not recognized by clang.

https://clang.llvm.org/docs/AttributeReference.html